The world's top memory chipmaker, Samsung Electronics, said it will launch independent reviews in response to reports that toxic materials used in chip making may have caused cancer in some of its employees.

South Korea's Samsung has been under pressure by some social and civic groups to take responsibility for the incidents, which were reported until late 2000s and for which a government investigation was conducted in 2007 and 2008.

The investigation concluded there were no problems at Samsung plants.

On Thursday, the company said 22 of its employees who worked at its chip plants had been diagnosed with leukemia or lymphoma, and between 1998 and 2010, 10 of them died of cancer.

Samsung said chemicals used during the chip making process at its plants had not caused the cancers.

Some of its affected employees have sought compensation from the government but have not launched a suit directly against Samsung.

We are deeply sorry about the loss of loved ones... and we've actively cooperated on epidemiologic investigations, which concluded there were no leaks of radiation, Cho Soo-in, president of Samsung's memory division, told reporters.

But I feel we should also have done this (communicated with the public) in the first place to stop speculation from growing, he said.

Cho was speaking at Samsung's sprawling chip manufacturing facility in the Seoul suburb of Kiheung, where its chip business first started in early 1980s.

We will do our best to improve the working environment and better communicate from now on, he said.

The old chip production lines where employees worked and later developed the illnesses were converted into chip test lines and light emitting diode production lines.

Samsung, which closely guards secrets of its chip production lines, showcased two current chip lines to the media on Thursday, including one it says was similar to the lines in question.

The lines, which require visitors to wear dust-proof attire from head to toe, have occasionally been opened for visiting high-profile politicians, including former Chinese president Jiang Zemin.

(Editing by Jon Herskovitz and Anshuman Daga)